The full potential of the elliptical arch was realized by a French engineer of Swiss ancestry, Jean-Rodolphe Perronet (1708–1794). While observing the slight tilt of the pier of a bridge under construction, Perronet realized that much of the stability of a completed arch bridge results from the transference of compressive forces through the bridge and towards its abutments. Perronet also understood that these forces could be made more horizontal by building bridges with arches that were as flat as possible. Perronet used these principles to design bridges with piers of unprecedented slimness. These slender piers conferred a number of advantages. In addition to saving material, the thin piers widened the waterways between them, facilitating the movements of boats on the river. Wider waterways also reduced the current passing through them, so less damage was done to the piers by the scouring action of the river’s current. [Arch Bridge]

Maillart’s design for the Zuoz Bridge had vertical walls, extending right to the abutments, which he imagined to be part of his hollow box. Such full-depth walls had been a crucial feature of ancient Roman bridges, even though they are structurally inefficient and sometimes require extra maintenance.

During the nineteenth century, such walls gradually became useless, but the image of “appropriate” form persisted even for Maillart until he noticed cracks at Zuoz in 1903. He realized immediately that these cracks were not dangerous for his reinforced concrete bridge. He further recognized that walls near the abutments were structurally useless. [The Art of Structural Design]

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Robert Maillart의 대표작인 Salginatobel Bridge
Maillart’s best-known structure is the Salginatobel Bridge, completed in 1930. The design was based on the hollow-box arch of the destroyed Tavanasa Bridge, but with refinements: Maillart eliminated……